Problem with an impeller pump that keeps on breaking

I realize that this may be somewhat of a long shot here, but my Johnson Model B bandsaw uses a Jabsco pump with an AL 1/4-37 impeller on it. It is a goofy looking rubber part, that looks as follows;
http://www.globalspec.com/ImageRepository/LearnMore/20137/impeller_500014e25452f264f6b953be27ff3570d4f.png/[img]

At any rate I have replaced the thing several times the one I am using was a 4528-0003-p which I think I correctly cross referenced. While I have had some luck with them lasting I am finding I go through these impellers quite regularly. The last one only lasted me about a day or two till the first vane broke off. I am wondering if I have a material compatibility issue I am using Mobilmet 426 oil on the vane. I see they offer them at least in nitrile and neoprene. I was wondering if it will make a difference, or if there is a preferable one?

I have seen from reading online that running these things dry can be an issue, however since Johnson mounted them so high up, inevitably especially when starting and priming them some dry running can be expected. I have tried putting a check valve in the plumbing to help somewhat but still my impellers just don't seem to last. Anyone have any ideas here?

Anyone else with this saw?

It may be compatibility. A half century ago (really) when I ran one we used soluble oil and had no problems. We might have changed one every 5 years.

2¢

If this a rubber impeller with the drive shaft offset in the bore, personal experience 5 seconds of running dry will kill it.